Knife



June l0, 1969 H. SKLAR 3,448,518

KNIFE Filed July 27, 1967 Ivm 1.1.11/ 1l 46 FIG. 7

ATTORNEY.

United States Patent O U.S. Cl. 30--162 5 Claims ABSTRACT OF THE DISCLOSURE A retractable blade knife having an elongate unitary handle with an open channel within which a knife blade is axially retractable. The channel is formed with a lower guide groove accommodating the tip of a securement screw. Overlying the guide groove in the channel is an intermediate blade carriage slideway of greater breadth than said guide groove, slidingly accommodating a blade carriage plate, and overlying the blade holder slideway is an upper "blade slideway slidably accommodating the blade for extension or retraction from the handle. A headed thumb screw extends through the blade and in threaded engagement through the blade holder to abut against the bottom of the guide groove, whereby the knife blade may be selectively positioned in varying degrees of extension with respect to the handle.

Background of the invention This invention relates to the art of retractable knives, and more particularly to an improved knife construction formed with a unitary handle lending itself to inexpensive lightweight production.

A variety of retractable blade knives have been evolved permitting retraction of the knife blade into the handle for storage purposes, such for example as shown by U.S. Patent 2,862,296. Such prior knives, though generally adequate for workshop use, do not lend themselves to being carried about as pocket knives since they are relatively bulky, and expensive due to the multiparted construction of their handles. Additionally, the mounting mechanism for the blade employed to permit extension and retraction of the blade into the handle generally does not provide for the security of locking of the blade in a retracted position which would be required were the knife to be carried around as a pocket knife. `Other problems arise in that the precise positioning of the blade at any specified degree of extension with respect to the handle is generally not available, since these prior art knives either provide for a stepped degree of extension, or locking in an extended or retracted position. Obtaining precise extension of the blade at a point intermediate the stops is substantially unattainable, preventing use of the blade for making a cut of a precise depth such as would be used in scoring for art purposes or the like. Other diiculties have arisen in prior art retractable knives in that the cutting edge of the blade becomes dulled -by rubbing against the inside surface of the handle during extension or retraction of the blade.

Summary It is with the above problems and desiderata in mind that the present improved knife has been evolved, a retractable blade knife provided with a unitary handle subject to being made of an extrusion, or by a simple milling process, of relatively small weight and bulk, and relatively inexpensive, with the blade subject to secure selective positioning at any degree of extension with respect to the handle, and subject to being locked in place in retracted position, thereby facilitating use of the knife as a pocket knife.

3,448,518 Patented June 10, 1969 ice It is accordingly among the primary objects of the invention to provide an improved retractable blade knife subject to being used as a pocket knife.

Another object of the invention is to provide a retractable blade knife subject to being manufactured at relatively low cost, with relatively little bulk or weight.

Another object of the invention is to provide a retractable blade knife in which the knife blade is subject to selective positioning at any degree of extension or retraction in a secure position with respect to the handle.

A further object of the invention is to provide a retractable blade knife in which the cutting edge of the blade is not damaged during extension or retraction.

These and other objects of the invention, which will lbecome hereinafter more apparent, are achieved by providing a retractable blade knife with an elongate unitary handle element `with an open channel having a lower guide groove dimensioned to accommodate the head of a thumb screw. Overlying the guide groove in the channel is an intermediate blade carriage slideway and overlying the blade holder slideway is a blade slideway formed by laterally extending slots in the channel. A knife blade is slidably positioned in said blade slideway, and a blade carriage of a plate like configuration is arranged within said blade carriage slideway. A thumbscrew extends through said knife blade and in threaded engagement through said blade carriage, with the tip end of the screw subject to abutment against the bottom of the guide groove so that upon tightening of said thumb screw to bring the tip thereof -against the guide groove, the blade carriage will move up to sandwich the blade "between the upper wall of the blade slideway slots and the blade carriage.

A feature of the invention resides in the provision of protuberances in the guide groove at the desired limit of movement of the blade with respect lto the handle.

Another feature of the invention resides in theformation of the blade slot on the cutting edge of the blade of a dimension such that the cutting edge of the 4blade does no contact the knife handle during its movement with re-. spect to the handle.

An additional feature of the invention resides in the formation of the knife handle with a beveled end adjacent the cutting edge of the knife blade so as to provide clearance for any kerf material cut by the knife. l

Brie)c description of the drawing ticularly pointed out in clear, concise, and exact terms in conjunction with the accompanying drawings, wherein:

FIG. l is a perspective view looking down at a knife made in accordance with the teachings of this invention, showing the channel formed in the unitary knife handle; and

FIG. 2 is a top plan view looking down at the handle of the knife shown in FIG. l, illustrating the protuberances employed for limiting movement of the knife blade with respect to the handle;

FIG. 3 is a slightly enlarged cross sectional view taken on line 3-3 of FIG. 1 illustrating the relationship of the knife compone-nts;

FIG. 4 is an enlarged transverse cross sectional view taken on line 4 4 of FIG. 1 illustrating the relative positioning of the blade with respect to the handle showing the clearance between the blade cutting edge and the handle;

FIG. 5 is a plan view of the blade carriage;

FIG. 6 is a detail view illustrating the kerf clearing chamfer on the knife handle; and

FIG. 7 is a plan View of a blade suitable for use in practicing the invention.

Description of the preferred embodiment Referring now more particularly to the drawing, like numerals in the various figures will be employed to rdesignate like parts.

As seen in FIG. 1, the knife 10 comprises an elongate handle 11 with open channel 12.

Channel 12 is formed with a cross sectional contour, as illustrated to the left of FIG. l, and in FIG. 4. The bottom of the channel 12 is formed with a guide groove 1'4 underlying an intermediate blade carriage slideway 16. Above the plane of carriage slideway 16, a blade slideway 18 is formed by means of slots 19 and 20. Slots 19 and 20 may be formed to extend an equal distance from the center line of the handle, or may be formed with the slot 19 extending a bit further from the handle center line than slot 20 to provide desired cutting edge clearance, or alternatively, the blade, as hereinafter described, may be positioned off center with respect to the handle center line.

Upstanding from the bottom surface of guide groove 14, as best seen in FIGS. 2 and 3 are end protuberances 22 and 23, and an intermediate protuberance 24. The protuberances 22, 23 and 24 are preferably formed by upsetting the Ibottom surface of handle 11 by punching or the like.

The knife handle contour, as best seen in FIGS. l, 2, and 4 is preferably of a trapezoidal configuration in plan view with ends 26 and 27 inclined towards each other. The cutting edge side of the handle is formed with bevels 28 and 29 to provide for kerf clearance, as will be hereinafter more fully described.

Mounted for sliding within the handle blade carriage slideway 16 is blade carriage 30, as best seen in FIGS. 3 and 5. The blade carriage 30 is formed of a plate dimensioned to slide freely within the carriage slideway 16 in handle 11, and having a relatively small extension as compared to the length of the handle 11, as best seen in FIG. 3. A threaded opening 32 is formed in the center of the blade carriage 30, and one or more blade engaging protuberances 33 are upset from the material of the blade holder.

A variety of different types of knife blades may obviously be employed in connection with handle 11. A preferred blade 35 is illustratively shown in FIG. 7 as formed of a trapezoidal configuration geometrically similar to the trapezoidal configuration of handle 11, and having ends 37 and 38 which extend parallel to the ends 26 and 27 of the handle 11. The cutting edge 40 of blade 35 is formed on the longer side of the blade 35. In the illustrated embodiment, the blade is shown as formed so that opposite ends thereof may be used for cutting, depending on which end of the blade is extended from the handle 11. In this arrangement, the blade is formed with a central aperture 41 slightly larger size than the aperture 32 in the blade carriage 30. Carriage engaging apertures 42 are dimensioned and positioned so as to snugly accommodate carriage protuberances 33 to permit minimal lateral play between the blade and the blade carriage. In the event that further stability of the blade with respect to the blade carriage 30 is desired, it will be understood that additional apertures in the blade and protuberances in the carriage 30 may be formed. Should a blade be utilized in connection with a knife which is intended for extension from only one side of the handle, this blade may either be formed with a pair of protuberance engaging apertures `42 on one side of the aperture 41, or may be formed with a variety of differently shaped apertures to effect desired locking of the blade with respect to the carriage 30. In the illustrated preferred embodiment, it is preferred to form the blade with a plurality of spaced score lines 46 parallel to the end of the blade, and therefore also parallel to the ends of the handle 11. In the event of dulling of the point of the blade, the score line forms a line of weakness permitting the blade to be broken off along the score line to renew the point thereof.

A selectively adjustable headed thumb screw 50, as best seen in FIGS. l and 3, is positioned to extend through aperture 41 in blade 35, and in threaded engagement through threaded aperture 32 in blade carriage 30. The screw 50 is of a length such as to extend from the upper surface 0f the handle 11, as seen in FIG. 3 t0 the bottom' surface of guide groove 14, with the tip 51 of screw 50 extending below the level of protuberances 22, 23 and 24 in guide groove 14. The head 52 of the thumb screw 50 is preferably edge knurled to permit ready gripping between the thumb and foreiinger of the user, and the dimensions of ythe head 51 are such that the diameter of the head is equal to the distance across the top surface of the handle 11, preferably with the knurling extending slightly over the edges of the top surface of the handle 11, as best seen in FIG. l

Operation The novel knife 10, above described, lends itself to fabrication in a variety of fashions. By virtue of the shaping 0f the handle 11 with channel 12, the handle lends itself particularly to fabrication from extruded bar stock. An aluminum extrusion formed with a channel 12, as illustrated in FIGS. l and 4, is found particularly suitable. The extruded bar stock having the requisite channel shape, is cut off to desired length and formed with the contours illustrated in FIG. 2. Protuberances 22, 23 and 24 are upset into the cut off length of bar stock by utilizing a punch, or the like, and the blade carriage 30 along with the knife blade 35 is positioned in the slideways formed by the channel 12, after which thumb screw 50 may readily be inserted.

As above described, the dimensioning of the carriage 30 with respect to the carriage slideway 16 is such that the carriage may freely slide in the slideway, but not be subject to skewing with respect to the axis of the handle 11.

The blade and carriage are slid by means of the thumb screw to any desired position with respect to the handle, and thereafter by tightening the thumb screw 50, the carriage 30 will be drawn up towards the top surface of the handle, as viewed in FIG. l, thus sandwiching the blade between the carriage and the upper surface of the blade slots 19 and 20 to maintain the blade in secure position.

As noted above, the blade slot 19 closest to the cutting edge 40 of the blade may be made slightly deeper than blade slot 20 so as to provide clearance between the sharp edge of the blade and the knife handle. Alternatively, the apertures 42 of the blade may be positioned slightly off center with respect to the blade so that the blade is oriented in the handle with clearance between the cutting edge of the blade and the blade slot.

In order to eect sliding of the blade with respect to the handle, only a slight loosening of the thumb screw 50 is required. The amount of loosening is not such as to draw the tip 51 of screw 50 above the extension of protuberances 22 and 23. As a result, inadvertent slippage of the blade out of the handle is prevented by protuberances 22 and 23 acting as end stops. In the event that the blade is a double ended blade as illustrated, with both ends of the blade intended to be extended from the handle, it is preferred that a central protuberance 24 be employed, the length of the knife blade on either side of the thumb screw 50 is selected as such that in order to have the opposite end of the blade extend from the handle, it will be necessary to positively loosen the screw to override central protuberance 24. As a result, inadvertent retraction of the blade will not cause the opposite end of the blade to extend from the handle.

In use, it will be noted that as best seen in FIG. 6, bevels 28 and 29 in the handle 11 provide clearance for l any kerf material cut by the cutting edge of the blade, thus facilitating use of the blade in the scoring o f soft materials tending to produce a large kerf.

The above disclosure has been given-by way of illustration and elucidation, and not by way of limitation, and it is desired to protect all embodiments of the herein disclosed inventive concept within the scope of the appended claims.

What is claimed is:

1. A retractable knife comprising an elongate unitary handle element formed with an open channel having a lower guide groove; an intermediate blade carriage slideway of greater breadth than said guide grove; and an upper blade slideway overlying said carriage slideway; a blade carriage slidably mounted in said carriage slideway; protuberances in said guide groove limiting the path of movement of said carriage; a blade removably supported on said carriage and sliding in said blade slideway; and a screw member passing in threaded engagement through said carriage to engage said carriage to sandwich the blade between said carriage and a wall of said blade slideway.

2. A knife, as in claim 1, in which said blade is formed with a peripheral boundary in plan view in the conflguration of a trapezoid geometrically similar to that of said handle, with a plurality of spaced score lines parallel to the ends of said blade, whereby blunted points on said blade may be broken off.

3. A knife, as in claim 1, in which the cutting edge of said blade is parallel to an edge of said handle, and the edge of said handle closest to said cutting blade is beveled ott at an angle away from said cutting edge to provide kerf clearance.

4. A knife, as in claim 1, in which said blade guideway is formed by laterally extending slots in opposite sides of said channel; and said blade is formed with a cutting edge positioned at a spaced distance from the inside edge of one of said slots, whereby rubbing of said blade will be avoided during extension and retraction of said blade with respect to said handle.

5. A knife, as in claim 1, in which said blade is secured to said carriage at a midpoint of said blade, whereby said blade may be extended from one or the other end of said handle.

References Cited UNITED STATES PATENTS 1,906,573 5/1933 Gits 30162 X 2,145,985 2/1939 Krajicek 30-162 X 2,870,537 1/1959 Ortner 30-162 2,904,884 9/1959 Baum 30-162 2,948,961 8/1960 Ortner 30-162 3,041,724 7/1962 Bobkowski 30-162 3,192,624 7/1965 Gringel 30-162 MYRON C. KRUSE, Primary Examiner.

U.S. Cl. X.R. -335, 346 

